Former and coil for printed circuit board assembly

ABSTRACT

The invention relates to a former and a coil for printed circuit board assembly, consisting of a prismatic or cylindrical coil form for at least one coil and a foot part, which is configured as one piece with the coil form, at least sections of said part protruding externally above the coil form. According to the invention, connecting wires for the coil or coils are formed from the coil wire and their ends are configured as solder terminals, which are housed and held in wire guides of the foot part.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/AT03/00037, filed Feb. 10, 2003 and claims the benefit thereof.The International Application claims the benefits of Austrianapplication No. 218/2002 filed Feb. 12, 2002, both of the applicationsare incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a coil former and a coil for circuit boardmounting, comprising a prismatic or cylindrical winding form for atleast one coil, and a base forming a single piece with said winding formand projecting out over said winding form at least in sections.

BACKGROUND OF INVENTION

In wound components, by which is essentially meant inductive componentsin the power supply area, the coils on a winding form are generallyconnected to pins by routing the wire ends of one or more coils tocorresponding solder pins, wrapping them around same and then solderingthem. In another known solution, the coil consists of a broad andrelatively rigid metal tape which can be soldered directly to aconductor track of a printed circuit board.

With the known solutions, either the labor input involved in fabricatingthe wound component as a whole is high, e.g. if the leads of the coilare to be soldered to solder pins, or difficulties arise with solderingto PCB conductor tracks, as is the case, for example, with the designusing a wound metal tape.

SUMMARY OF INVENTION

The object of the invention is to simplify the design of the woundcomponent for ease of mounting on a printed circuit board, therebyreducing costs.

This object is achieved according to the invention by forming leads forthe one or more coils from the latters' winding wire and implementingthem with their ends as solder pins which are accommodated in wireguides of the base and retained therein.

Thanks to the invention, one operation, namely the soldering of the coilto separate solder pins, can be dispensed with during fabrication of thecoil former with the coil, and therefore of the wound component. As theends of the winding wire are accommodated in the wire guides of the baseand retained therein, there is produced a defined spacing of the solderpins corresponding to the drilled holes provided on the printed circuitboard.

In a useful variant, wire guides are implemented in opposite sections ofthe base relative to the coil axis, resulting in increased stability ofthe wound component disposed on the printed circuit board.

In another useful variant it is provided that the wire guides areimplemented as drilled holes in the base through which one end of thecoil wire can be inserted, thereby providing a simple means of immovablyfixing the solder pins.

On the other hand it may also be expedient for the wire guides to beimplemented as outwardly open grooves in the base into which one end ofthe coil wire can be inserted from the outside. This variant is usefulif the wire is relatively stiff because of its diameter or materialcharacteristics, so that threading it through drilled holes afterwinding could prove difficult, it being advantageous in view of thedesired secureness of the solder pins if the grooves are narrowedtowards the outside, the coil wire snapping into place.

In a particularly practical variant it is provided that in one sectionof the base at least one wire guide is implemented as a drilled hole andin an oppositely located section at least one wire guide is implementedas an open groove. This embodiment provides on the one hand highstability and accuracy of fit of the solder pins and, on the other,allows ease of fabrication even with relatively stiff winding wire.

In usual and useful embodiments of the invention, the coil wire has adiameter of 1 to 4 mm and the coil wire is advantageously implemented ascopper wire.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with further advantages will now be explained ingreater detail with reference to embodiments illustrated in theaccompanying drawings in which

FIG. 1 shows a plan view of a first embodiment of the invention,

FIG. 2 shows a side view in the direction of the arrow II of FIG. 1,

FIG. 3 shows a side view in the direction of the arrow II of FIG. 1,

FIG. 4 shows a plan view of a coil former according to FIGS. 1 to 3,wound and provided with a core

FIG. 5 shows the former-coil-core arrangement as in FIG. 4 but in sideview, soldered onto a printed circuit board,

FIG. 6 shows a view as in FIG. 5, but seen from the opposite side,

FIG. 7 shows a plan view of another possible embodiment of a coil formerfalling within the scope of the invention, and

FIG. 8 shows another embodiment of a coil former in a plan view, similarto FIG. 7.

DETAILED DESCRIPTION OF INVENTION

As may be seen from FIGS. 1 and 2, a coil former 1 consists of acylindrical winding form 2 and a base 3 forming a single piece withsame. The entire coil former 1 is made of a plastic material such aspolyamide, produced e.g. by injection molding. Of course, any materialssuitable for the relevant application in terms of their electrical,thermal and mechanical properties can be used for the coil former 1.

In this case the base 3 is rectangular and projects—not visible in planview—out over the winding form 2 all round. Of importance for theinvention are two sections 3 a, 3 b which are opposite relative to thecoil axis 1 and in which wire section 3 b and two outwardly open grooves5 in the other section 3 a. As may be best seen from FIG. 1, the grooves5 are narrowed towards the exterior, so that there is provided a snapfit for a wire of suitable diameter pressed into the grooves fromoutside. The drilled holes 4 and the grooves 5 run parallel with thecoil axis a.

FIGS. 4 to 6 show the wound coil former according to FIGS. 1 to 3. Inthis case a winding or coil 6 is formed from two parallel wound wires 7,8 e.g. made of enameled copper wire. For fabrication of the coil 6, thewires 7,8 with their beginnings are inserted through the drilled holes 4(FIG. 5), the coil 6 is wound onto the winding form 2 and then the endsof the wires 7,8 are guided downward and placed in the grooves 5. Thedownward protruding ends of the wires 7,8 are shortened until theyprotrude a few millimeters above the drilled holes 4 or grooves 5,thereby forming solder pins 9. Using said solder pins 9, the woundcomponent can be mounted on a printed circuit board 10 and soldered, asindicated in FIG. 5.

It can therefore be seen that with the invention the otherwise customaryseparate leads for the solder pins are formed by the winding wire of thecoil and merge directly into the solder pins as one piece.

In the embodiment according to FIGS. 4 to 6, the coil 6 is completed byan E-core 11 consisting of two halves, plastic spacers 12 glued into theair gap also mechanically fixing the two core halves. The winding of thecoil 6 can if required also be fixed using adhesive, e.g. an artificialresin. The asymmetrical arrangement of the solder pins 9 ensures correctmounting of the entire wound component on a printed circuit board 10.

In the exemplary embodiment shown, the coil 6 is a single winding whichis, however, dual-wound in order to allow a high current density withreduced spin effect and moderate wire diameter. All variants of coils orwindings are possible within the scope of the invention. In the case ofan individual, single-wound coil, two terminals or solder pins willnaturally also suffice. A coil former suitable for this purpose is showne.g. in FIG. 7, only one groove 5 and one drilled hole 4 being providedas wire guides in the base 3.

Of course the term “coil” should here likewise also include tappedwindings, such as a plurality of windings of a transformer ortransducer. In these cases also, three or more solder pins will berequired. FIG. 8 shows an embodiment in which the winding form 2possesses an approximately square cross section, two grooves 5 and twodrilled holes 4 being implemented as wire guides in the base 3.

1. A coil former, comprising: a coil for printed circuit board mounting;a prismatic or cylindrical winding form for at least one coil; a baseprojecting out over said winding form at least in sections; and leadsfor the one or more coils being formed by the latters' winding wire andimplemented with their ends as solder pins which are accommodated andretained in wire guides implemented as outwardly open grooves in thebase, wherein the grooves are narrowed towards the outside, the coilwire snapping into place and the solder pins are asymmetricallyarranged.
 2. The coil according to claim 1, wherein in one section ofthe base at least one wire guide is implemented as a drilled hole and inan opposite section at least one wire guide is implemented as an opengroove.
 3. The coil former according to claim 1, wherein the coil wirehas a diameter of 1 to 4 mm.
 4. The coil former according to claim 2,wherein the coil wire has a diameter of 1 to 4 mm.
 5. The coil formeraccording to claim 1, wherein the coil wire is a copper wire.
 6. Thecoil former according to claim 2, wherein the coil wire is a copperwire.
 7. The coil former according to claim 3, wherein the coil wire isa copper wire.
 8. A coil former with coil for printed circuit boardmounting, comprising: a prismatic or cylindrical winding form for atleast one coil; a base projecting out over said winding form at least insections; and leads for the at least one coil being formed by thewinding wire of the coil, wherein the leads are implemented with theirends as solder pins which are accommodated and retained in wire guidesimplemented as outwardly open grooves in the base, wherein the groovesare narrowed towards the outside, the coil wire snapping into place byinsertion, and wherein the solder pins are asymmetrically arranged forcorrect mounting.
 9. The coil former according to claim 8, wherein thebase is a foot part.
 10. The coil former according claim 1, the windingform is shaped to carry an E-core.
 11. The coil former according claim8, the winding form is shaped to carry an E-core.
 12. The coil formeraccording claim 1, the grooves have a smaller diameter towards theoutside and a broader diameter towards the inside.
 13. The coil formeraccording claim 8, the grooves have a smaller diameter towards theoutside and a broader diameter towards the inside.